Variable condenser



March 28, 1933. D ASBURY 1,903,157

VARIABLE CONDENSER Filed Aug. 14, 1929 6 Sheets-Sheet l 32 LUZ March 28, 1933.

D. F. ASBURY VARIABLE CONDENSER Filed Au 14, 1929 6 Sheets-Sheet 2 March 28, 1933 D, ASBURY 1,903,157

VARIABLE CONDENSER Filed Aug. 14, 1929 6 Sheets-Sheet 3 D. F. ASBURY 1,903,157

VARIABLE CONDENSER Filed Aug. 14, 1929 6 Sheets-Sheet 4 Mafcli 28, 1933. ASBURY 1,903,157

VARIABLE CONDENSER Filed Aug. 14, 1929 6 Sheets-Sheet 5 March 28, 1933. s u 1,903,157

VARIABLE CONDENSER Filed Aug. 14, 1929 e sneex-sheet s Patented Mar. 28, 1933 PATENT OFFICE DOBSEY F. ASBURY, OF BROOMES ISLAND, MARYLAND,

VARIABLE CONDENSER Application filed August 14, 1929. Serial No. 385,889.

.My invention relates to radio apparatus and has particular reference to improvements in variable condensers of the plate type which have two sets of plates relatively movable interdigitatingly to produce various amounts of overlapping area between the plates.

More particularly when any plurality of condensers which embody the principles of my invention are installed in a radio apparatus their collectively movable sets of plates may be moved to a first, a second and a third position to produce respectively a first, a second and a third amount of overlapping area with the other sets of plates and while the collectively movable sets of plates are in their said first, second and third positions the said other set of plates of each condenser can be moved in their own planes respectively in a first, a second and a third direction to find and establish the amount of overlapping area necessary to electrically balance the condensers for the said first, second and third positions of the collectively movable sets of plates. The condensers being in perfect balance for three spaced positions of the collectively movable sets of plates are far nearer in balance for all other positions of the collectively movable sets of plates than they would be if they were merely balanced for a mid position for the two other corrections not only balance but they reduce the angle of diversion of the curve I of the variable individual to each of the condensers.

In the drawings wherein like characters of reference denote corresponding parts in the different views Figure 1 is a plan view of two condensers made in accordance to my invention;

' Figure 2, a transverse section on lines 2-2 of Fig. 1 showing the rotor plates in their 25 rotary position.

Figure 3 shows side and end views of the dielectric eccentrics which support, insulate and shift the stators.

Figure 4, a transverse section similar to Fig. 2 showing the rotor plates in their 150 rotary position,

Figure 5, a transverse section similar to Fig. 2 showing the rotor plates in their 90 rotary position;

Figure 6, a view similar to Fig. 1 showing a modified form of the means constituting my present invention; 5

Figure 7, a transverse section on line 7--7 of Figure 6 showing the rotor plates in their 30 rotary position Figure 8, a transverse section similar to Figure 7 and showing the rotor plates in their 150 rotary position;

Figure 9, a transverse section similar to Figure 7 showing the rotor plates in their 90 rotary position.

Figure 10, a similar view to Figure 1 showing a modified form of the means constituting my present invention;

Figure 11, a transverse section on line 11-11 of Figure 10 showing the rotor plates in their 150 rotary position; 76

Figure 12, a transverse section similar to Figure 11 showing the rotor plates in their 30 rotary position;

Figure 13, a transverse section similar to Figure 11 showing the rotor plates in their 90 rotary position;

Figure 14 shows the shape of the stator plates shown in Figures 10 to 13; and

Figure 15 shows side and end views of oneof the dielectric double eccentrics which sup- 86 port, insulate and shift the stators shown in Figures 10 to 13.

Referring to the drawings Figures 1 to 5 inclusive the two condensers 15 and 16 respectively have sets of rotor plates 17 and 18 and sets of stator plates 19 and 20. There are twelve plates in each set of rotors all of wh'ch are fixed to the same shaft 21 and this shaft has reduced end portions 22 and 23 which fit in bearing holes in the frame end plates 24 and 25. The frame end plates are I held in parallel spaced relation by the four brace rods 26, 27,28 and'29 which are all the same length and have reduced end portions 30 fixed to the end frame plates by nuts 31. The brace rod 26 is located near the shaft 21 and acts to stop the rotors when they are rotated to their wide open or fully closed positions. The eccentric members 32, shown in detail by Figure 3, are made of insulating material and at one end is a reduced diameter portion 33 eccentric to the hole 35 and at the other end is a hexagon nut portion 36. 0n each of the brace rods 27 28 and 29 are mounted two eccentric members 32, insulating washers 37 and a coil spring 38 between the washers, all for a purpose which will presently appear. Each stator 19 and is composed of twelve thin side plates 39 and one thick center plate 40. The side plates 39 have projecting lugs 41 and 42 and the center plate 40 is the same shape as the side plates except that the projecting lugs project farther and have made therein slots 43, 44 and 45 having a width equal to the diameter of the eccentrics 33. The thin side plates 39 are fixed to the thick center plate 40 by bolts 46 and nuts 47. Each of the stators'19 and 20 are supported in the condensers by the slots 43, 44, and 45 in its center plates 40 straddling an eccentric 33 on brace rods 27, 28 and 29 respectively. The thickness of the center plate 40 is greater than the depth of the eccentric 33 and the coil springs 38 pressing against washers 37 holds the stator plate yieldable in their own planes and parallel to the rotor plates. All of the eccentric members are shown in all the views with their eccentrics in their midthrow position.

Figure 2, shows the rotor 17 in a position of 25 from its open position and by rotating the eccentric on brace rod 27 to the right or left the throw of the eccentric will slightly rotate the stator plates about the eccentric on brace rod 28 to respectively increase or decrease the amount of the overlapping area between the stator and rotor plates as desired. While the rotor plates are still in this 25 position of rotation the stator plates may be slightly rotated about point 48 by rotating the eccentric on bracevrod 28 without changing the amount of overlapping area, for the places where the edges of the stator and rotor plates cross are equal distance from point 48 and the stator plates may be slightly shifted to left or right by rotating the eccentric on brace rod 29 without changing the amounts overlapping area for this 25 rotary position.

Figure 4, shows the rotor in a position of 150 rotation from the open position and by rotating the eccentric on brace rod 28 to the left or right the throw of the eccentric will slightly rotate the stator plates about point 48 to respectively increase or decrease the amount of overlapping area between the stator and rotor plates as desired. While the rotor plates are still in this 150 rotary position the stator plates may be slightly shifted on the eccentrics on the brace rods 27 andv 28 by rotating the eccentric on brace rod 29 without changing the amount of overlapping area, for that area which goes on or off due to lug 41 will be equal in amount to that which respectively goes off or on due to lug 42, lugs 41 and 42 being of equal width. The front edges of the rotor plates in the 150 position are parallel to the line of shift.

Figure 5, shows the rotor plates in a posi tion of 90 rotation from the open position and by rotating the eccentric on brace rod 29 to the right or left the throw of the eccentric will slightly shift the stator plates to the left or right respectively to increase or decrease the amount of overlapping area between the stator and rotor plates as desired. The amount of change due to this shifting is equal to the amount of area which goes on or OK at the front edge of the rotor plates minus that amount which respectively goes off or on due to the lug 41. Lug 42 may be located in line with lug 41; and in this position the amount of change of overlapping area for the 90 position of the'rotor due to shifting the stator would be greatly increased for the same amount of area which would go off or on at lug 41 would go on or ofi' respectively at lug 42 and the whole amount of change due to the stator plates being shifted 011 or off the front edge of the rotor plates would be effective, but it is thought best to keep lug 42 where it is shown for other reasons.

During rotation of the rotor plates while they are engaging in overlapping relation with the lugs 42 on the'stator plates the line frequency curve of the condenser would'have a hump in it if the cut-out 49 were not made in the stator plates. Lug 42 is not only nee essary as a. support but it is there to balance the area of lug 41 for the 150 position of the rotor plates while the stator'plates are being shifted to get the desired area for the 90 position of the rotor plates.

I have proven above (see Fig. 2) that the eccentric on brace rod 2 is the only one that can materially change theamount of overlapping area between the stator and rotor plates for the 25 position of rotation of the rotor plates. I have also proven above (see Fig. 4) that the eccentric onbrace rod 28 is effective to make a change in the amount of overlapping area for the 150 position of rotation ofthe rotor plates and have proven that the eccentric on brace rod 29 is effective to make a change in the amount of overlapping area for the 90 position of rotation of the rotor plates and ineffective to change the overlapping area established by the eccentric on brace rod 28 for the 150- position of the rotor plates. Therefore the amount of overlapping iarea between therotor and stator plates for 25 rotation of the rotor plates can be changed as desired and permanently established and the amount of overlapping area between the rotor and stator plates for 150 rotation of the rotor plates'can be changed as desired and permanently established and the amount of overlapping area between the rotor and stator plates for 90 rotation of the rotor plates can also be changed as desired and permanently established. The change in the amount of overlapping area for the 25 and 150 rotary positions of the the capacity of the condenser for the 25 and 150 rotary positions of the rotor plates, the 25 position is for a less capacity and 'the 150 is for a greater capacity, this change for the mean position of the rotor plates simply decreases or increases the capacity below amean higher rotary position and the capacity of the condenser is changed for all rotary positions of the rotor plates except for the 25 and 150 rotary position (see Fig. 3) of the rotor plates is equal to the amount of area of the stator plates which goes on or off at the front edge of the rotor plates minus the amount which goes off or on respectively between the circular dashed lines 50 and 51. The same amount of area of the stator plates between the circular lines 52 and 53 which goes on or off at the front edge of the rotor plates goes off or on at the lug '42. The center for these circular lines 50, 51, 52 and 53 is the point 48 about which the stator plates are slightly rotated to make the change. The

amount of area of the stator plates between the circular lines 50 and 51 which goes on or off the rotor plates is comparatively very small for this section of the stator plates is ver close to the point 48.

Re erring to the group of Figs. 6, 7, 8 and 9 the sets of rotor plates 54 and 55 are fixed to the shaft 56 and this shaft is mounted for rotation in the end frame plates 57 and 58 and these end frame plates are held in spaced and parallel relation by the four brace rods 59, 60, 61 and 62. On each end of the brace rod 60, 61 and 62 is mounted for rotation an insulating member 63 the inner end of which is provided with an eccentric 64 and near the outer end is a hexagon nut portion 65 for a wrench to adjust the eccentric by. The wrench to be used is better when made of dielectric material. Inwardly of the eccentric is mounted an insulating washer 66 and inwardly of the washer is a disc spring 67 and between the disc springs is a distance or spacing member 68. The plates of each stator 69 and 70 are all the same shape and are fixed to a centrally located supporting member 71 by lugs 72, 73 and 74 which project across the ath of rotation of the rotor plates and are olted to the said supporting member. The supporting member 71 is provided with three slots 75, 76 and 77 which are assembled astride the eccentrics on brace rods 60, 61 and 62 respectively. The supporting members 71 of each stator is held yieldably tight between the insulating members 63 and the insulating washers 66 and the said tightness depends on' the strain under assembled.

Referrin to Fig. 7, which shows the rotor plates in t eir 30 position of rotation the which'the di'sc springs 67 are width of the stator plates where they overlap 70 with front edge of the rotor plates is bisected and a vertical line is drawn through the point of bisection and in this line as high up as good construction will allow the center of the eccentric 64 on brace rod 60 is located. On Fig.

8, which shows the rotor plates in their 150 position of rotation a line is drawn through .the bisection point of the width of the stator plates and perpendicular to the said 150.

these lines intersect at the point 78. A hori zontal line is drawn through point 78 and in this line is located the eccentrics which are on brace rods 61 and 62. The front edges of the rotor plates where they intersect the edges of the stator plates when in the 30 rotary position are circular about the point 78 and the other portion of the front edges which intersect the edges of the stator plates when in the 150 rotary position, shown in Fig. 8, are

circular about the same point 78 and the inner and outer edges of the stator plates where they intersect with the front of. the rotor plates when in their 30 rotary position are circular about the eccentric on brace rod 62.

Fig. 9, shows the rotor plates in their rotary position.

With the rotor plates in their 30 rotary position (see Fig. 7) the eccentric on brace rod 60 may be rotated to the left or right to slightly rotate the stator platesabout the eccentric on brace rod 62 to increase or,deerease- 1 respectively the amount of overlapping area between the rotor and stator plates by the amounts shown between the dashed lines below and above the front edges. With the rotor plates in their 150 rotary position (see Fig. 8) the eccentric on brace rod 61 may be rotated to the left or right to slightly slide the stator plates on the eccentrics on the brace rods 60 and 62 to increase or decrease respectively the amount of overlapping area between the rotor and stator plates by the amounts, shown between the front edges and the dashed lines to the right and left, without materially chan ing the amount of over- 1 lap established for t e 30 rotary position of the rotor plates. The amount of change of overlap ing area due to this sliding of the stator p ates is equal to that area which goes on or off at the front edge of the rotor plates minus that which goes off or on respectively at the lugs 72, the lugs 73 due' to their location are ineffective to produce a material change. With the rotor plates in their 90 rotary position (see Fig. 9) the eccentnic on brace rod 62 may be rotated to the right or left to slightly rotate the stator plates about point 78 to increase or decrease respectively the amount of overlapping area between the rotor and stator plates, by the amounts shown between the front edges and the dashed lines to the right and left, without changing the amount-of area between the plates of the rotor and stator for the 30 and 150 rotary position of the rotor plates. The amount of change of the overlapping area for the 90 rotary position is that area which goes on or off at the front edge of. the rotor plates minus the area which goes off or on respectively at lugs 72. The lugs 73 being of equal width to that of the lugs 72 and equal distance from point 78 when the stator is slightly rotated to produce a change in amount of overlapping area for the 90 rotary position no change in amount of overlapping area for the 150 rotary position is produced'by the lugs for the amount that goes on or oil at lugs 72 goes off or on respectively at lugs 73.

Referring to the group of Figures 10 to 15, the sets of rotor plates 79 and 80 are fixed to the shaft 81 and this shaft is mounted for rotation in the end frame plates 82 and 83 and these end frame" plates are held in spaced parallel relation by the four brace rods 84, 85, 86 and 87 On each end of the brace rods 85, 86 and 87 inside of the end frame plates is mounted for rotation an insulating member 88, shown in detail by Fig. 15, the outer end of which is provided with a hexagon nut portion 89 and inwardly of this hexagon nut and also on the inner end are cylindrical portions 90 and 91 both. in line with'each other and eccentric to the hole 92. Inwardly of this insulating member is an insulating washer 93 and between the washers 93 is a bent disc spring 94. Each of the stators 95 and 96 is composed of eleven thin plates 97 between two thick side plates 98 which support the stator. The thin plates 97, (see Fig. 14) each have a wide supporting lug 99 and another supporting lug 100 made as narrow as possible to leave it strong enough to serve its only purpose, that being a support for that end of the plates. The thick side plates 98 are the same shape except their supporting lugs extend farther and have made therein slots 101, 102 and 103 having a width equal to the diameter of the eccentric portions 90 and 91. The thin stator plates are fixed to these thick side plates by bolts 104 and nuts 105. The lug on the thick stator plates which corresponds to lug 100 on the thin stator plates is made wider for more strength. Each of the'stators 95 and 96 are supported in the condenser by the slots 101, 102 and 103, which are in the thick side plates, 98, straddling the eccentric portions 90 and 91 of the insulating members 88 or brace rods 85, 86 and 87 respectively. The depth of the eccentric portion 91 is less than the thickness of the thick side plates 98 and the bent disc springs 94: holds the inwardly located side plates of each condenser. The strength of the spring 94 is such that the stator plates may be slightly moved in their own planes. The eccentric of the front edges of the rotor plates and in this line is located the center of the eccentric .portions 90 and 91 of the insulating member 88 on brace rod 85. The center of the ecpen: tric on brace rod 86 is located in a plane including the straight front edges of the rotor plates when they are in their 30 rotary position. The brace rod 87 has no critical location except that it should be out of line with brace rods and 86 to form a better support. From the center of the eccentric on brace rod 87 is drawn a line perpendicular to the line from point 106 through the center of eccentric on brace rod 6 and these lines intersect at a point 107. The center of the circular portion of the front edges of the rotor plates is the point 108 which is 60 from the point 106 and the same distance from the center of the rotor shaft 81. The slots 101 and 103 are parallel to each other and perpendicular to the slot 102.

\Vith the rotor plates in their 30 rotary position, shown in Fig. 12, the eccentrics on brace rod 85 may be rotated to the right or left respectively to increase or decrease the amount of overlapping area. While the rotor plates are still in this 30 position the rotation of the eccentrics on the brace rods. 86 and 87 is ineffective to produce a change in the amount of overlapping area between the stator and rotor plates. lVith the rotor plates in their rotary position, shown in Fig. 13, the eccentrics on brace rod 86 may be rotated to right or left to respectively move the stator plates farther on or off of the rotor plates to increase or decrease the amount of overlapping area and while the rotor plates are in this 90 rotary position the eccentrics on brace rod 87 are ineffective to produce a change of overlapping area for the stator would rotate about the point 108 which is coincident with point 106 and the front edges of the rotor plates where they cross the inside and outside edges of the stator plates are circular. about the point 106. With the rotor plates in their 150 rotary position, shown in Fig. 11, the eccentrics on brace rod 87 may be rotated to the left or right to respectively move the stator plates farther on or off of the rotor plates to increase or decrease the amount of overlapping area. To make .a larger change than would otherwise be produced the cut-out 109 is made in the front portions of the thin stator plates between the circular dashed lines 110 and 111 and the por tions of the thick side plates between the circular dashed lines 110 and 112 are ineffective to produce achange in the amount of area but the portions of all the stator plates outside of the circular dashed line 110 and the portions of the thin stator plates, between the circular dashed lines 111 and 112 are effective to produce a change.

The order of making these area corrections is first, for the 30 rotary position of the rotor plates and is made by rotating the stator; second, for 90 and is made by sliding the stator; third, for 150 and is made by rotatin the stator. The order in which the correctlon of area for Figs. 1 to 5, is; first, for 25 and is made by rotating the stator; second, for 150 and is made by rotating the stator and third, for 90 made by sliding the stator. The order in which the area corrections are made for Figures 6 to 10 is; first, for 30 and is made by rotating the stator; second, for 150 and is made .by sliding the stator; third, for 90 and is made by rotating the stator. The first and second rotary positions in the order of area corrections made are critical but the third correction may be made with the rotors stopped short of or beyond the degrees of rotation specified for the last area correction. The largest area corrections can be made by the design shown by Figs. 10 to 15. It is admitted that there is a minute error produced for the first and second rotary position when the third correction is made, if a first and second correcti n were made, but the said minute error p duced is several hundred times smaller than the amount of the third correction and therefore the said error is only theoretical in amount and it would take an instrument far more sensitive than the human ear to detect same, therefore this method is correct for all intheir own planes three times, each time in a different direction.

What I claim is:

1. A condenser, comprising in combination, a plate, a second plate and means for moving it in its own plane to produce amounts of overlapping area between it and the first said plate, and means whereby the first saidplate may be moved back and forth in each of three diflerent directions to respec tively find and establish the desired amounts of overlapping area between the plates for three certain amounts of movement of the said second plate. I

2. A condenser, comprising in combina tion, two sets of plates and means for rotaabout two axes and bodily moved in the direction from one axis to the other to move the plates minor amount in their own planes in three different directions.

3. A condenser comprising in combination, a plate, a second plate movable major amounts to produce major amounts of overlapping area between the plates, and means whereby the first said plate may be moved in its own plane in two disalined directions without changing the amount of overlapping area between the plates for a certain position in the movement of the second plate.

4. A condenser comprising in combination, a plate, a second plate movable to a plurality of certain positions in a plane parallel to the first plate, and means for adjusting the first plate in its own plane while the second plate is stationary in each certain position to establish a desired amount of overlap between the plates and without changing a previously established amount of overlap for any other certain position of the second plate, said first plate, after the adjustment thereof for each of the certain positions of the second plate, remaining stationary during all movement of the second plate.

In testimony whereof I hereunto aifix my signature.

DORSEY F. ASBURY. 

